1. Field of the Invention
The present invention relates to a module for transferring a printed circuit board (PCB) during manufacture and an apparatus for attaching a PCB to a liquid crystal display device.
2. Background of the Related Art
PCBs have commonly been used to operate electric devices, such as display devices. A PCB is fabricated by printing signal lines on a glass fiber or a plastic substrate and attaching electric elements to the substrate. Recently, due to rapid development of semiconductor integration technology, a TCP (tape carrier packaging) technology for wireless bonding has been suggested as a packaging technology for LSI (large scale integration), VLSI (very large scale integration) and ULSI (ultra large scale integration) semiconductor chips. The TCP technology is a packaging technology that uses TAB (tape automated bonding) technology where a semiconductor chip is joined with a film and sealed up with resin, and the TCP technology includes COF (chip on film or chip on flexible printed circuit).
As the TCP technology has been employed, the range of appropriate uses of a PCB has increased. For example, a PCB can be used to operate a liquid crystal display (LCD) device with the TCP film.
As illustrated in FIG. 1, a liquid crystal panel 2 includes first and second substrates 4, 6, with a liquid crystal layer between the two substrates 4, 6. The liquid crystal panel 2 is connected to gate and data PCBs 12, 14. The liquid crystal panel 2 is normally operated as an active matrix. On an inner surface of the first substrate 4, a plurality of gate and data lines are arranged to define a plurality pixel regions in a matrix form. A plurality of thin film transistors are arranged at crossing portions of the gate and data lines and connected to a plurality of pixel electrodes in the plurality of pixel regions. The inner surface of the second substrate 6 includes a black matrix that provides shielding to the gate and data lines and the thin film transistor, a color filter located in the pixel region, and a common electrode where the black matrix and the color filter are arranged.
The gate PCB 12 is connected to the gate lines to supply gate signals to the gate lines. The data PCB 14 is connected to the data lines to supply data signals to the data lines. For example, the gate PCB 12 may sequentially supply On gate signals to the gate lines, which sequentially turns on the thin film transistors. When the thin film transistors are turned on, data signals are supplied to the pixel electrodes through the data lines. Since the common electrode is supplied with a common voltage, an electric field is induced in the liquid crystal layer by a voltage difference between the pixel electrode and the common electrode. The alignment of the liquid crystal molecules in the liquid crystal layer changes in accordance with the intensity and direction of the induced electric field, thereby changing the light transmissivity of the LCD device. A backlight unit (not shown) is disposed below the liquid crystal panel 2, to supply light to the liquid crystal panel 2.
The PCBs 12, 14 are connected to the liquid crystal panel 2 through at least one TCP film 20. The TCP film 20 is attached to the PCBs 12, 24 and the liquid crystal panel 2 through first and second anisotropic conductive films (ACFs) 22, 24 that form conductive bonding agents at both ends of the TCP film 20.
Connection of the PCBs 12 and 14 to the liquid crystal panel 12 is conducted as follows. The steps of adhering the first ACF 22 to the PCBs 12, 14 and attaching the TCP 20 to the liquid crystal panel 2 with the second ACF 24 are performed separately. The PCBs 12, 14 are attached to the TCP 20, which was previously attached to the liquid crystal panel 2, with the first ACF 22 adhered to the PCBs 12, 14. These attaching processes are conducted in a PCB attaching apparatus.
As illustrated in FIG. 2, a related art PCB attaching apparatus includes a first attaching portion 30, a second attaching portion 50 and a delivery device 40 connecting the first and second attaching portions 30, 50. The first attaching portion 30 includes a loading part 32, a first attaching part 34, and an unloading part 36. The second attaching portion 50 includes an inspection part 52 and a second attaching part 54.
The first attaching portion 30 further includes a PCB transfer module 60 transferring a PCB (12, 14 of FIG. 1) in the first attaching portion 30. The PCB transfer module 60 makes a trip along a moving path Land passes the loading part 32, the first attaching part 34, and the unloading part 36. The PCB supplied to the loading part 32 is transferred to the first attaching part 34 using the PCB transfer module 60 where an ACF (22 of FIG. 1) is adhered to the PCB, then the PCB with the ACF 22 is transferred to the unloading part 36 using the PCB transfer module 60.
The PCB at the unloading part 36 is delivered to the inspection part 52 with a delivery device 40 such as a pickup robot. In the inspection part 52, the electrical connection between the bonded PCB and ACF are inspected.
The PCB with the ACF is then transferred to the second attaching part 54. At this time, the TCP film (20 of FIG. 1) that previously was attached to a liquid crystal panel (2 of FIG. 1) with another ACF (24 of FIG. 1) is prepared. Accordingly, the PCB is attached to the TCP film with the ACF previously adhered to the PCB. Meanwhile, the second attaching portion 50 may further include another transfer module 62 that transfers the PCB from the inspection part 52 to the second attaching part 54.
As illustrated in FIG. 3, the PCB transfer module 60 includes a pair of guide rails 70 and a transfer body 80. The guide rails 70 pass though a loading part 32, a first attaching part 34 and an unloading part 36 along the moving path (L of FIG. 2) of the transfer module 60, with the transfer body 80 sliding forward and backward on the guide rails 70. The transfer body 80 includes a supporter 82 that fixedly supports a plate 84. The PCB is placed on the plate 84 to be transferred. Accordingly, the transfer body 80 transfers the PCB between the loading part 32 and the unloading part 36.
Because the related art PCB attaching apparatus and the PCB attaching method depend on a single transfer body 80 to transfer the PCB between stations, total process time is longer than necessary, which makes production inefficient.
Specifically, the number of the LCD devices fabricated in the second attaching portion 50 is limited by the number of cycles the transfer body 80. Additionally, the PCB attaching process is completely stopped when the transfer body 80 is secured for repairs. In addition, the transfer module 62 of the second attaching portion 50 remains idle while the transfer body 80 transfers the PCB from the loading part 32 to the unloading part 36 via the first attaching part 34, and also while the transfer body 80 returns to the loading part 32 without the PCB and transfers new PCB to the unloading part 36. Therefore, efficiency of the related art PCB attaching apparatus is greatly reduced with use of the transfer module 62 of the second attaching portion 60.
To solve these problems, the speed of the transfer body may be increased. However, the speed of the transfer body must be limited to maintain stability. Alternatively, multiple guide rails and multiple transfer bodies can be used. However, the multiple transfer bodies start at the same loading part 32, return to the same unloading part 36, and meet at the same first attaching part 34. Accordingly, the use of multiple transfer bodies would require waiting a period of time to avoid bottlenecks at the starting point, the meeting point, and the returning point. Additionally, if the PCB attaching apparatus was provided with multiple transfer bodies would need a large installation space.